Homeopathic medicine and weight loss supplements are legal scams.
Not all weight loss supplements are scams, and not all are legal. Are large percentage of advertised weight loss supplements (perhaps even a majority) are
illegal scams because they're using false advertising.
Similarly with homeopath.
Not all companies claiming to use MLM are scams, and not all are legal. Indeed it's quite possible, even probable, that at any given time most companies that advertise themselves as MLM are not legitimate MLM and are in fact illegal pyramids. That doesn't make MLM a legal scam, it makes these companies illegal pyramids.
When you look at the top direct selling companies though, virtually all of which use multi-level compensation plans, many of them have been around for many many decades and have been thoroughly investigated and cleared, both of fraud and other illegal activities.
This is technically illegal, but some scammers figure out ways to get away with it.
If it's technically illegal then it's illegal full stop.
Many of these companies get investigated by the SEC and/or the FBI, and some even get prosecuited and shut down(and sometimes the executives get short prison sentences), but all too many are allowed to continue to exist.
Why? Is it because they're legal or a lack of resources?
They will often
change their name and ticker symbol to hide a very ugly history of
fraudulent activity.
sounds like they're actually illegal, just haven't been caught
Oh and even though the SEC discovered that 80% of GllobeTel/Sannswire/World Surveilance Group's revenues were fraudulent, and the former CEO is in prison, it is still allowed to trade! It has "new management".
One would hope that means something has changed that allowed them to keep operating. Again though, sounds like they weren't operating legally before at all, so are just plan old scams, not legal scams.
It sounds to me like what you're referring to as illegal and/or scam isn't the MLM part - it's more something to do with a scam product, or false advertising etc etc. All things which are
already illegal.